1. Field of the Invention
The present invention relates to a semi-automatic shift implementation control system/method for semi-automatic shifting of a lever-shifted mechanical transmission, preferably a compound transmission of the range and/or splitter type. More particularly, in a preferred embodiment of the present invention, a splitter or combined splitter-and-range-type compound transmission is provided with controls and actuators for forward lever shifting with automatic splitter shifting and automatic engine control to cause torque breaks for shifting into neutral and/or to synchronize for engaging the target gear ratio. A controller is provided with means to sense an operator intent to shift into neutral and is responsive to cause the engine to be fueled to minimize torque lock and/or initiate a splitter shift. A manually operated intent-to-shift switch may be utilized.
2. Description of the Prior Art
Compound range-type mechanical transmissions using so-called "double-H" type controls wherein a range shift is automatically selected by movement of the shift lever, without requiring the operator to use a button or lever to select a range change, are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 3,429,202; 4,561,325; 4,455,883; 4,663,725 and 4,944,197, the disclosures of which are incorporated herein by reference.
Compound mechanical transmissions of the combined splitter-and-range type are widely used for heavy-duty vehicles and very well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665; 4,944,197; 5,193,410 and 5,390,561, the disclosures of which are incorporated herein by reference.
Semi-automatic shift implementation systems for compound mechanical transmissions wherein, upon manual shifting into a highest grouping of gear ratios, automatic shifting within only that highest grouping is provided, are known in the prior art and are disclosed in U.S. Pat. Nos. 4,722,248 and 5,038,627, the disclosures of which are incorporated herein by reference. Semi-automatic shift implementation systems for mechanical transmissions wherein the vehicle operator is required to manually cause a torque interruption and/or achieve synchronous conditions are known in the prior art and are disclosed in U.S. Pat. No. 5,053,961, the disclosure of which is incorporated herein by reference.
At least partially automated systems wherein engine fuel control, such as engine dither, is utilized to cause non-torque-lock conditions for shifting into neutral without requiring master clutch manipulation are known in the prior art and are disclosed in U.S. Pat. Nos. 4,850,236 and 5,105,357, the disclosures of which are incorporated herein by reference.
U.S. Pat. No. 5,435,212, the disclosure of which is incorporated herein by reference, discloses a semi-automatic shift implementation system which, for each lever position, has automatic splitter shifting, which allows a "(2+1).times.(2).times.(2)" type compound 10-speed transmission to be driven with the ease of a 5-speed automatic transmission.
The above systems, as disclosed, were not totally satisfactory for certain applications, as the operator was possibly required to manipulate the splitter control and/or the throttle and/or master clutch for lever shifts.